Volume 1, Issue 2 (October 2016)

Original research papers



Stanislav Pavelka

Pages: 155-158

DOI: 10.21175/RadJ.2016.02.029

Received: 22 MAR 2015, Received revised: 11 MAY 2015, Accepted: 18 MAY 2015, Published Online: 18 OCT 2016

Recently, we have shown in the isolated rat thyroids marked effects of excessive exogenous bromide and perchlorate ions on the activity of thyroid peroxidase (TPO), the key enzyme in thyroid hormones (TH) metabolism. Here, we studied in more details, with the aid of several radioanalytical methods, the effects of an enhanced bromide and/or perchlorate intake on various aspects of iodine metabolism and, consequently, on TH metabolism in the rat. Goitrogenic and thyrotoxic effects of excessive bromide and perchlorate ions were followed in adult male rats, maintained on diets with various iodine content, ensuring either sufficient iodine supply or mild to severe iodine deficiency. In rats administered with these xenobiotics, we measured a consistent increase in relative weight of the thyroids with increasing time and concentration of applied bromide, and a sharp reduction of the 24-h uptake of [131I]-iodide by their thyroids. In these animals, we also determined a steady decline in serum total thyroxine concentration. At the molecular level, we found, unexpectedly, that the influence of exogenous bromide on the TPO enzyme activity in the rat thyroids was not simply inhibitory. It was more complex, biphasic with regard to the extent of bromide intake in the animals. With the use of several radioanalytical methods, including adapted radiometric determination of TPO enzyme activity, we therefore confirmed and quantified the presumed thyrotoxic effects of xenobiotics bromide and perchlorate ions.
  1. S. Pavelka, “Bromine” (Chapter 9.3), in Elements and Their Compounds in the Environment. Occurrence, Analysis and Biological Relevance, 2nd ed., vol. III, E. Merian, M. Anke, M. Ihnat and M. Stoeppler, Eds. Weinheim: Wiley-VCH Verlag, 2004, pp. 1445-1455.
    DOI: 10.1002/9783527619634.ch60c
  2. S. Pavelka, “Metabolism of bromide and its interference with the metabolism of iodine”, Physiol. Res., vol. 53 (Suppl. 1), pp. S81-S90, 2004.
  3. S. Pavelka, “Iodine transfer through mother’s milk: The influence of bromide” (Chapter 20), in Comprehensive Handbook of Iodine, V.R. Preedy, G.N. Burrow and R. Watson, Eds. Oxford: Academic Press, 2009, pp. 199-206.
    DOI: 10.1016/B978-0-12-374135-6.00020-0
  4. 4. S. Pavelka, “Bromide interference with iodine metabolism: Goitrogenic and whole-body effects of excessive inorganic bromide in the rat” (Chapter 61), in Comprehensive Handbook of Iodine, V.R. Preedy, G.N. Burrow and R. Watson, Eds. Oxford: Academic Press, 2009, pp. 587-595.
    DOI: 10.1016/B978-0-12-374135-6.00061-3
  5. S. Pavelka, “Radioiodine tracers as useful tools in studies of thyrotoxic effects of exogenous bromide and perchlorate ions”, J. Radioanal. Nucl. Chem., vol. 291, pp. 405-408, 2012.
    DOI: 10.1007/s10967-011-1191-y
  6. T. Nakashima and A. Taurog, “Improved assay procedures for thyroid peroxidase: application to normal and adenomatous human thyroid tissue”, Clin. Chim. Acta, vol. 83, pp. 129-140, 1978.
    DOI: 10.1016/0009-8981(78)90216-4
  7. L.E. Braverman and R.D. Utiger (Eds.), Werner and Ingbar’s the Thyroid. A Fundamental and Clinical Text, 8th ed. Philadelphia: Lippincott Williams & Wilkins, 2000.
  8. F.X.R. Van Leeuwen, R. Hanemaaijer and J.G. Loeber, “The effect of sodium bromide on thyroid function”, Arch. Toxicol., vol. 12 (Suppl.), pp. 93-97, 1988.
    DOI: 10.1007/978-3-642-73113-6_14